WP10.3 LHC Crab Cavities Overview EUCARD SRF Annual Review Peter McIntosh (STFC, ASTeC, Daresbury Laboratory)

Outline The Collaboration Team Description of the Scientific Work Project Planning Deliverables and Milestones Publications

The Collaboration Team CERN (Switzerland) Fellow (New appointment) 18 m.m. from May 2010 CERN Total 18 m.m. ULAN-CI (UK) RA-Cavity (P Ambattu) 18 m.m. RA-LLRF (I Tahir) 10 m.m. Academic-Cavity (G Burt) 4 m.m. Academic-LLRF (A Dexter) ULAN-CI Total 36 m.m. All in post UMAN-CI (UK) PDRA-Cavity (A D’Elia) 16 m.m. Academic-Cavity (R Jones) 2 m.m. UMAN-CI Total 18 m.m. All in post STFC (UK) WP Coordinator (P McIntosh) 4 m.m. RF Engineer (P Goudket) 10 m.m. Mech Designer (Undefined) STFC Total 18 m.m.

WP10.3 LHC Crab Cavities Design, build and test a single LHC and CLIC crab cavity structure, including input coupler, mode couplers and tuners. Design, build and test a LLRF and synchronization system that meets the crab cavity phase and amplitude control specifications for LHC and CLIC. If the beam time and the necessary hardware become available, validate and test the assembled crab system solutions (as part of wider collaboration teams) and LLRF control systems on LHC and CTF3 in 2011; otherwise make performance predictions based on the measured noise characteristics.

LHC-CC Local vs Global Local crab crossing preferable (Phase-II): Independent control at IPs, Avoid collimation/impedance issues. Need compact cavities to fit in the IR region of the ring. Lower frequency hopefully! Small crossing angle (~0.5 mrad): Global crab scheme is ideal choice for prototype Phase-I: Test feasibility of crab crossing in hadron colliders, Address all RF and beam dynamic issues, Small orbit excursion and tune shifts, Compatible with nominal and upgrade options to recover the geometric luminosity loss, Collimation optimisation! These cavities are feasible using available technology and the gradient requirements are within reach of current technology.

LHC US-LARP Integration (Phase-I)

LHC US-LARP Integration (Phase-II)

LHC-CC09 CERN: 16-18 Sept 09 After the success of KEKB, CERN must pursue crab cavities for the LHC; the potential luminosity increase is significant. Machine protection is possible show stopper. Effect of fast cavity changes to be looked at with high priority. Impedance is concern as LHC (and SPS) revolution frequency changing during acceleration, and detuning of the cavity may be more difficult than for KEKB, strong damping of the dipole mode might need to be examined. Demonstration experiments with beam should focus on the differences between electrons and protons (e.g. effect of crab-cavity noise with beam-beam, impedance, beam loading) and on reliability & machine protection which are critical for the LHC; beam test with a (KEKB?) crab cavity in another proton machine (SPS?) may be useful and sufficient. Both “global” and “local” crab schemes retained as options. Future R&D focus should be on compact cavities, which can be installed in the IR regions of IP1 and 5 as local cavities for the LHC upgrade phase II. Modifications of IR4 during the 2013/14 shutdown should be looked at; the IR4 region could be used for the installation and test of compact crab-cavity prototypes and for accommodating a possible global crab-cavity scheme. The crab cavity infrastructure should be kept in mind for all other LHC upgrades. Steve Myers (CERN Director of Accelerators) conclusions

CLIC-CC Developments

Crab Cavity LLRF Solutions LHC-CC Full digital system anticipated, based on ILC-CC R&D. Interferometer synchronisation. Stability tolerance expected: <0.04% and 0.003o @ 8 mrad. CLIC-CC Hybrid digital-analogue system anticipated. Analogue adjustment during the bunch train. Digital for train to train optimisation of control loop. Timing tolerance expected: 6 fs. Interferometer required between cavities. Synergetic with ILC development.

10.3 Project Plan and Milestones

WP10.3 Milestones Number Title Output Month M10.3.1 LHC crab cavity specifications completed R M12 M10.3.2 LHC model crab cavity completed P M24 M10.3.3 LHC input and LOM mode coupler design development finished P/R M33 M10.3.4 CLIC crab cavity specifications completed M10.3.5 CLIC model crab cavity completed M10.3.6 CLIC input and mode coupler design development finished M10.3.7 Development of LHC LLRF system M21 M10.3.8 Development of CLIC LLRF system M30

WP10.3 Deliverables WP1: LHC-CC Design (F Zimmerman, CERN) WP2: CLIC-CC Design (R Jones, UMAN-CI) WP3: LHC-CC and CLIC-CC LLRF (A Dexter, ULAN-CI) Number Title Output Month 10.3.1 LHC crab cavity final report R M36 10.3.2 CLIC crab cavity final report 10.3.3 LHC and CLIC LLRF final reports

Publications Publications Events Status of LHC Crab Cavity Simulations and Beam Studies, R Calaga et al Particle Accelerator Conference 2009, Vancouver, 2009. LHC Upgrade Scenarios, F Zimmermann et al Wakefield Damping for the CLIC Crab Cavity, P Ambattu et al Status of LHC Crab Cavity Cryostat, N Solyak et al Novel Geometries for the LHC Crab Cavity, B Hall et al Study with One Global Crab Cavity at IR4 for LHC, Y Sun et al Tune Shift due to Crossing Collision and Crab Collision, Y Sun et al New Cavity Shape Developments for Crabbing Applications, G Burt Superconducting RF Conference 2009, Berlin, 2009. Events EuCARD ACCNET workshop on LHC crab cavities, “LHC-CC09,” at CERN, 16-18 Sept 2009 ICFA Deflecting Cavity Mini-Workshop, at Cockcroft Institute, 21-23 April 2010

WP10.3 Review Programme WP10.3 LHC Crab Cavities Overview P McIntosh (STFC) 10 mins LHC-CC Design and Optimisation G Burt (ULAN-CI) 20 mins CLIC-CC Design and Optimisation P Ambattu (ULAN-CI) 20 mins Crab Cavity LLRF Studies A Dexter (ULAN-CI) 20 mins LHC-CC Integration at CERN E Ciapala (CERN) 20 mins

ICFA Deflecting Cavity Mini-Workshop 21st – 23rd April 2010 Hosted at Cockcroft Institute http://www.cockcroft.ac.uk/events/cavity/